U.S. patent number 9,556,844 [Application Number 14/622,488] was granted by the patent office on 2017-01-31 for nozzle with contoured orifice surface and method of making same.
This patent grant is currently assigned to Caterpillar Inc.. The grantee listed for this patent is Caterpillar Inc.. Invention is credited to Lucas Burger, Matthew I. Rowan.
United States Patent |
9,556,844 |
Rowan , et al. |
January 31, 2017 |
Nozzle with contoured orifice surface and method of making same
Abstract
A nozzle for a member of a fuel combustion system of an engine
includes a hollow nozzle body. The nozzle body includes an outer
surface, an inner surface, and an orifice surface. The outer
surface defines an outer opening. The inner surface defines an
interior chamber and an inner opening. The orifice surface defines
an orifice passage extending between, and in communication with,
the outer opening and the inner opening. The orifice passage is in
communication with the interior chamber via the inner opening. The
orifice surface includes a boundary surface and a protrusion. The
protrusion projects from the boundary surface radially inwardly
into the orifice passage.
Inventors: |
Rowan; Matthew I. (Chillicothe,
IL), Burger; Lucas (Lafayette, IN) |
Applicant: |
Name |
City |
State |
Country |
Type |
Caterpillar Inc. |
Peoria |
IL |
US |
|
|
Assignee: |
Caterpillar Inc. (Peoria,
IL)
|
Family
ID: |
56620974 |
Appl.
No.: |
14/622,488 |
Filed: |
February 13, 2015 |
Prior Publication Data
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|
|
Document
Identifier |
Publication Date |
|
US 20160237971 A1 |
Aug 18, 2016 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B05B
1/265 (20130101); F02M 61/184 (20130101); B05B
1/262 (20130101); F02M 51/061 (20130101); B05B
1/02 (20130101); B22D 23/00 (20130101); B05B
1/267 (20130101); F02M 47/025 (20130101); F02M
47/02 (20130101); F02M 61/1806 (20130101); B05B
1/3046 (20130101); F02M 61/1833 (20130101); F02P
13/00 (20130101); B33Y 10/00 (20141201); B33Y
80/00 (20141201) |
Current International
Class: |
F02M
61/00 (20060101); F02M 61/18 (20060101); B05B
1/26 (20060101); F02M 47/02 (20060101); F02M
51/06 (20060101); B22D 23/00 (20060101); B05B
1/30 (20060101); B05B 1/02 (20060101); B33Y
10/00 (20150101); B33Y 80/00 (20150101) |
Field of
Search: |
;239/500,502,522,533.8,533.9,533.11,533.12,584,585.1,596,601 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2700796 |
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Feb 2014 |
|
EP |
|
1358910 |
|
Apr 1964 |
|
FR |
|
WO 2009/130376 |
|
Oct 2009 |
|
WO |
|
Primary Examiner: Ganey; Steven J
Attorney, Agent or Firm: Leydig, Voit & Mayer, Ltd.
Claims
What is claimed is:
1. A nozzle for a member of a fuel combustion system of an engine,
the nozzle comprising: a nozzle body, the nozzle body being hollow
and including an outer surface, an inner surface, and an orifice
surface, the outer surface defining an outer opening, the inner
surface defining an interior chamber and an inner opening, and the
orifice surface defining an orifice passage extending between, and
in communication with, the outer opening and the inner opening, the
orifice passage being in communication with the interior chamber
via the inner opening; and wherein the orifice surface includes a
boundary surface and a protrusion disposed adjacent the inner
opening, the protrusion projecting from the boundary surface
radially inwardly into the orifice passage, and wherein the
protrusion is configured to divert a flow of a fuel mixture/flame
front entering the orifice passage from the inner opening radially
away from the boundary surface.
2. The nozzle according to claim 1, wherein the boundary surface is
generally cylindrical and has a lower portion and an upper portion,
and the protrusion projects from the upper portion of the boundary
surface.
3. The nozzle according to claim 2, wherein the protrusion extends
circumferentially over a segment of the upper portion.
4. The nozzle according to claim 3, wherein the protrusion includes
a first inclined surface and a second inclined surface, the first
inclined surface and the second inclined surface in converging
relationship to each other and defining a ridge, the first inclined
surface extending between the inner opening and the ridge and
inclined away from the boundary surface moving from the inner
opening to the ridge, the second inclined surface extending between
the ridge and the boundary surface at an intermediate edge thereof,
the second inclined surface inclined toward the boundary surface
moving from the ridge to the intermediate edge.
5. The nozzle according to claim 1, wherein the protrusion
comprises a first protrusion, and the nozzle further comprises: a
second protrusion, the second protrusion projecting from the
boundary surface radially inwardly into the orifice passage, the
second protrusion being discontinuous from the first
protrusion.
6. The nozzle according to claim 5, wherein the boundary surface is
generally cylindrical and has a lower portion and an upper portion,
the first protrusion projects from the upper portion of the
boundary surface, the second protrusion projects from the lower
portion of the boundary surface, and the second protrusion includes
a convex surface and a concave surface, the convex surface disposed
adjacent the inner opening, and the concave surface disposed
axially outward of the convex surface from the inner opening toward
the outer opening.
7. The nozzle according to claim 1, wherein the boundary surface is
generally cylindrical and has a lower portion and an upper portion,
and the protrusion projects from the lower portion of the boundary
surface.
8. The nozzle according to claim 7, wherein the protrusion
comprises a convex spherical portion.
9. The nozzle according to claim 7, wherein the protrusion
comprises a torus segment.
10. The nozzle according to claim 7, wherein the protrusion is one
of a plurality of protrusions, each of the plurality of protrusions
projecting from the boundary surface radially inwardly into the
orifice passage.
11. The nozzle according to claim 10, wherein at least one of the
plurality of protrusions is circumferentially offset with respect
to at least one other of the plurality of protrusions about the
boundary surface.
12. The nozzle according to claim 10, wherein the orifice passage
extends along an orifice axis, and the plurality of protrusions is
generally circumferentially aligned with respect to each other
about the boundary surface and is in spaced relationship to each
other along the orifice axis.
13. The nozzle according to claim 12, wherein the plurality of
protrusions extends along the orifice axis substantially between
the inner opening and the outer opening.
Description
TECHNICAL FIELD
This patent disclosure relates generally to a fuel combustion
system for an internal combustion engine and, more particularly, to
a nozzle of a member of a fuel combustion system for an internal
combustion engine.
BACKGROUND
One type of internal combustion engines typically employ a number
of cylinders which compress a fuel and air mixture such that upon
firing of a spark plug associated with each cylinder, the
compressed mixture ignites. The expanding combustion gases
resulting therefrom move a piston within the cylinder. Upon
reaching an end of its travel in one direction within the cylinder,
the piston reverses direction to compress another volume of the
fuel and air mixture. The resulting mechanical kinetic energy can
be converted for use in a variety of applications, such as,
propelling a vehicle or generating electricity, for example.
Another type of internal combustion engine, known as a compression
ignition engine, uses a highly-compressed gas (e.g., air) to ignite
a spray of fuel released into a cylinder during a compression
stroke. In such an engine, the air is compressed to such a level as
to achieve auto-ignition of the fuel upon contact between the air
and fuel. The chemical properties of diesel fuel are particularly
well suited to such auto-ignition.
The concept of auto-ignition is not limited to diesel engines,
however, and has been employed in other types of internal
combustion engines as well. For example, a self-igniting
reciprocating internal combustion engine can be configured to
compress fuel in a main combustion chamber via a reciprocating
piston. In order to facilitate starting, each main combustion
chamber is associated with a prechamber, particularly useful in
starting cold temperature engines. Fuel is injected into not only
the main combustion chamber, but also the combustion chamber of the
prechamber, as well, such that upon compression by the piston, a
fuel and air mixture is compressed in both chambers. A glow plug or
other type of heater is disposed within the prechamber to elevate
the temperature therein sufficiently to ignite the compressed
mixture. The combustion gases resulting from the ignition in the
prechamber are then communicated to the main combustion
chamber.
Other types of internal combustion engines use natural gas as the
fuel source and include at least one piston reciprocating within a
respective cylinder. A spark plug is positioned within a cylinder
head associated with each cylinder and is fired on a timing circuit
such that upon the piston reaching the end of its compression
stroke, the spark plug is fired to thereby ignite the compressed
mixture.
In still further types of internal combustion engines, prechambers
are employed in conjunction with natural gas engines. Given the
extremely high temperatures required for auto-ignition with natural
gas and air mixtures, glow plugs or other heat sources such as
those employed in typical diesel engines, can be ineffective.
Rather, a prechamber is associated with each cylinder of the
natural gas engine and is provided with a spark plug to initiate
combustion within the prechamber which can then be communicated to
the main combustion chamber. Such a spark-ignited, natural gas
engine prechamber is provided in, for example, the 3600 series
natural gas engines commercially available from caterpillar Inc. of
Peoria, Ill.
Spark-ignited engines typically have very high component
temperatures. The temperature is a result of the gas flow and gas
temperature characteristics. In particular, the surfaces defining
the orifices of the nozzle of a member of a fuel combustion system,
such as a prechamber, for example, can be subjected to very high
temperatures. In the case of a prechamber assembly, the high
temperatures can be caused by the velocity of the fuel/air mixture
entering the nozzle through the orifices and the ignition flame
front discharged from the nozzle out through the orifices. As a
result, the high temperatures to which the orifices are subjected
can cause degradation of the nozzle and impair the function of the
nozzle over time.
U.S. Patent Application Publication No. 2013/0000598 is entitled,
"Divided-Chamber Gas Engine," and is directed to a gas engine that
is configured to inject a combustion gas from an auxiliary
combustion chamber through a plurality of nozzles, through which
the auxiliary combustion chamber and a main combustion chamber are
in communication with each other, so as to ignite a fuel in the
main combustion chamber. An opening edge, at the auxiliary
combustion chamber side, of each of the plurality of nozzles is
formed to have a curved surface.
There is a continued need in the art to provide additional
solutions to enhance the performance of a component of a fuel
combustion system to improve its efficiency and useful life. For
example, there is a continued need to protect the orifices of a
nozzle of a prechamber assembly from the extreme temperature to
which it can be subjected.
It will be appreciated that this background description has been
created by the inventors to aid the reader, and is not to be taken
as an indication that any of the indicated problems were themselves
appreciated in the art. While the described principles can, in some
respects and embodiments, alleviate the problems inherent in other
systems, it will be appreciated that the scope of the protected
innovation is defined by the attached claims, and not by the
ability of any disclosed feature to solve any specific problem
noted herein.
SUMMARY
In an embodiment, the present disclosure describes a nozzle for a
member of a fuel combustion system of an engine. The nozzle
includes a hollow nozzle body. The nozzle body includes an outer
surface, an inner surface, and an orifice surface. The outer
surface defines an outer opening. The inner surface defines an
interior chamber and an inner opening. The orifice surface defines
an orifice passage extending between, and in communication with,
the outer opening and the inner opening.
The orifice passage is in communication with the interior chamber
via the inner opening. The orifice surface includes a boundary
surface and a protrusion. The protrusion projects from the boundary
surface radially inwardly into the orifice passage.
In yet another embodiment, a method of making a nozzle for a member
of a fuel combustion system of an engine is described. The method
of making includes manufacturing a nozzle body. The nozzle body is
hollow and includes an outer surface and an inner surface. The
outer surface defines an outer opening. The inner surface defines
an interior chamber and an inner opening.
An orifice surface is defined. The orifice surface defines an
orifice passage extending between, and in communication with, the
outer opening and the inner opening. The orifice passage is in
communication with the interior chamber via the inner opening.
The orifice surface is defined such that the orifice surface
includes a boundary surface and a protrusion. The protrusion
projects from the boundary surface radially inwardly into the
orifice passage.
Further and alternative aspects and features of the disclosed
principles will be appreciated from the following detailed
description and the accompanying drawings. As will be appreciated,
the principles related to fuel combustion systems, nozzles for a
member of a fuel combustion system of an engine, and methods of
making nozzles for a member of a fuel combustion system of an
engine disclosed herein are capable of being carried out in other
and different embodiments, and capable of being modified in various
respects. Accordingly, it is to be understood that both the
foregoing general description and the following detailed
description are exemplary and explanatory only and do not restrict
the scope of the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatic, longitudinal cross-sectional view of an
embodiment of a fuel combustion system constructed in accordance
with principles of the present disclosure and including an
embodiment of a prechamber assembly constructed in accordance with
principles of the present disclosure.
FIG. 2 is an enlarged, detail view of a nozzle constructed in
accordance with principles of the present disclosure, as indicated
by circle II in FIG. 1, and suitable for use in the prechamber
assembly of FIG. 1.
FIG. 3 is an axial end view of an orifice of the nozzle of FIG. 1,
taken from an interior chamber of the nozzle.
FIG. 4 is a diagrammatic, longitudinal cross-sectional view of
another embodiment of a nozzle constructed in accordance with
principles of the present disclosure, the nozzle being suitable for
use in embodiments of a prechamber assembly following principles of
the present disclosure.
FIG. 5 is an enlarged, detail view of the nozzle of FIG. 4, as
indicated by rectangle V in FIG. 4.
FIG. 6 is an axial end view of an orifice of the nozzle of FIG. 4,
taken from an interior chamber of the nozzle.
FIG. 7 is an axial end view, as in FIG. 6, of another embodiment of
a nozzle constructed in accordance with principles of the present
disclosure, the nozzle being suitable for use in embodiments of a
prechamber assembly following principles of the present
disclosure.
FIG. 8 is an axial end view, as in FIG. 6, of still another
embodiment of a nozzle constructed in accordance with principles of
the present disclosure, the nozzle being suitable for use in
embodiments of a prechamber assembly following principles of the
present disclosure.
FIG. 9 is a partial axial cross-sectional view of an orifice of the
nozzle of FIG. 8 taken along line IX-IX in FIG. 8.
FIG. 10 is a flowchart illustrating steps of an embodiment of a
method of making a nozzle for a member of a fuel combustion system
of an engine following principles of the present disclosure.
It should be understood that the drawings are not necessarily to
scale and that the disclosed embodiments are sometimes illustrated
diagrammatically and in partial views. In certain instances,
details which are not necessary for an understanding of this
disclosure or which render other details difficult to perceive may
have been omitted. It should be understood, of course, that this
disclosure is not limited to the particular embodiments illustrated
herein.
DETAILED DESCRIPTION
The present disclosure provides embodiments of a nozzle for a
member of a fuel combustion system of an engine. In embodiments,
the member, such as a prechamber assembly or a fuel injector, for
example, can be mounted to a cylinder head of an internal
combustion engine. Exemplary engines include those used in
vehicles, electrical generators, and pumps, for examples.
Embodiments of a nozzle constructed according to principles of the
present disclosure can have an orifice configuration that helps to
reduce the heat transfer between a flow of fuel mixture/flame front
passing through the respective orifice of the nozzle and the nozzle
body and to reduce the temperature within the orifice passages and
the orifice bridges disposed around the nozzle body. In
embodiments, the nozzle can include an orifice surface having at
least one protrusion configured to modify a flow of a fuel
mixture/flame front passing through the orifice passage defined by
the orifice surface to help reduce at least one of the temperature
within the orifice passage and the heat transfer between the flow
of a fuel mixture/flame front and the boundary surface of the
orifice surface. Embodiments of a nozzle constructed according to
principles of the present disclosure can be made using additive
manufacturing techniques.
In embodiments, a nozzle constructed according to principles of the
present disclosure can include an orifice passage having at least
one protrusion configured to modify fluid flow through the orifice
passage relative to the same orifice passage without the
protrusion(s). In embodiments, a nozzle constructed according to
principles of the present disclosure can include an orifice passage
having at least one protrusion configured to help control flow
through the orifice passage such that the heat transfer between the
flow of fuel mixture/flame front and the boundary surface of the
orifice passage is reduced. In embodiments, the protrusion can be
configured based upon computer modeling to enhance flow streamlines
of the fuel mixture/flame front passing through the orifice
passage.
In embodiments, a nozzle constructed according to principles of the
present disclosure can be used in a suitable member of a fuel
combustion system of an engine, such as, a fuel injector or a
prechamber assembly, for example. In embodiments, a prechamber
assembly including a nozzle constructed according to principles of
the present disclosure can be associated with a supplemental fuel
source adapted to direct a flow of fuel into the precombustion
chamber of the prechamber assembly through a path other than via
the main combustion chamber in the cylinder block with which the
prechamber assembly is associated. In such embodiments, a control
valve, such as a conventional check valve arrangement, can be
provided to selectively permit the flow of fuel from the
supplemental fuel source into the precombustion chamber of the
prechamber assembly to further promote ignition within the
precombustion chamber. In embodiments, the fuel of the supplemental
fuel source can have a richer fuel/air ratio than the fuel/air
ratio of the fuel supplied directly to the main combustion chamber
with which the prechamber assembly is associated.
In embodiments, the ignited mixture within the prechamber is
discharged through the rippled orifices of the nozzle as a flow of
a flame front into the main combustion chamber with reduced heat
transfer effects as a result of the protrusions projecting into the
respective orifice passages. The flame area produced by a
prechamber assembly constructed according to principles of the
present disclosure can help improve combustion of a lean fuel
mixture in the main combustion chamber of the cylinder with which
it is associated.
Turning now to the FIGURES, there is shown in FIG. 1 an exemplary
embodiment of a fuel combustion system 20 constructed in accordance
with principles of the present disclosure. The fuel combustion
system 20 can be used in any suitable internal combustion engine,
such as an engine configured as part of an electrical generator or
a pump, for example. The fuel combustion system 20 can be used with
any suitable fuel with an appropriate fuel/air ratio. In
embodiments, fuels with different ignition and burning
characteristics and different specific fuel to air ratios can be
used. The fuel combustion system 20 can include a cylinder block
22, a cylinder head 24, a prechamber assembly 25 having a nozzle 50
constructed in accordance with principles of the present
disclosure, a supplemental fuel source 27, and a variety of other
combustion devices, as will be appreciated by one skilled in the
art.
Referring to FIG. 1, the cylinder block 22 defines, at least
partially, a main combustion chamber 30. In embodiments, the
cylinder block 22 can define a plurality of cylinders 32 (one of
which is shown in FIG. 1) within which is defined the corresponding
main combustion chamber 30. In embodiments, a cylinder liner can be
disposed within each cylinder 32. The cylinder liner can be
removably secured in the cylinder block 22.
The cylinder head 24 can be removably attached to the cylinder
block 22 via suitable fasteners, such as a plurality of bolts, as
will be appreciated by one skilled in the art. A gasket (not shown)
can be interposed between the cylinder block 22 and the cylinder
head 24 to seal the interface therebetween. The cylinder head 24
typically has bores machined for engine valves (not shown), e.g.,
inlet and exhaust valves, and other members of the fuel combustion
system 20 (not shown), e.g., fuel injectors, glow plugs, sparks
plugs, and combinations thereof, as will be appreciated by one
skilled in the art. In other embodiments, the fuel combustion
system 20 can include a fuel injector having a nozzle constructed
according to principles of the present disclosure.
Each cylinder 32 of the cylinder block 22 can house a reciprocally
movable piston (not shown), which is coupled to a crankshaft via a
suitable transfer element (e.g., a piston rod or connecting rod).
The piston is reciprocally movable within the cylinder 32 for
compressing and thereby pressurizing the combustible mixture in the
main combustion chamber 30 during a compression phase of the
engine. In embodiments, the engine can be configured to have a
suitable compression ratio suited for the intended purpose of the
engine as will be understood by one skilled in the art.
In embodiments, at least one intake valve mechanism (not shown) and
at least one exhaust valve mechanism (not shown) can be operatively
positioned within the cylinder head 24 such that the intake valve
and the exhaust valve are axially movable in the cylinder head 24.
In embodiments, a mechanical valve train (e.g., including a cam,
follower, and push rod mechanism) or other hydraulic and/or
electric control device can be used in a conventional manner to
selectively operate the intake valve mechanism and the exhaust
valve mechanism. In particular, the inlet valve mechanism can be
opened to admit a predetermined amount of a lean gaseous
combustible mixture of fuel and air directly into the main
combustion chamber 30 above the piston during an intake phase of
the engine. The exhaust valve mechanism can be opened to permit the
exhaust of the gases of combustion from the main combustion chamber
30 during an exhaust phase of the engine.
The cylinder head 24 and the cylinder block 22 can also define
cooling passages therein that are configured to cool members of the
fuel combustion system 20. In embodiments, any suitable cooling
system can be placed in fluid communication with the cooling
passages to circulate a coolant fluid through the cooling passages
in the cylinder block 22 and the cylinder head 24.
The prechamber assembly 25 is removably secured in the cylinder
head 24 such that the prechamber assembly 25 is in communication
with the main combustion chamber 30. The prechamber assembly 25
defines a precombustion chamber 34, which is in communication with
the main combustion chamber 30. The prechamber assembly 25 includes
a prechamber housing 42, an ignition device 44 adapted to
selectively ignite a fuel disposed in the precombustion chamber 34,
a control valve 48, and the nozzle 50. The nozzle 50 and the
prechamber housing 42 can be made from any suitable material, such
as a suitable, heat-resistant metal. Suitable sealing devices 52,
such as o-rings, for example, can be disposed between the
prechamber assembly 25 and the cylinder head 24. In other
embodiments, other sealing techniques, such as, press fit, metal
seals, and the like, can be used.
The nozzle 50 and the prechamber housing 42 cooperate together to
define the precombustion chamber 34 and to define a central
longitudinal axis LA of the prechamber assembly 25. The nozzle 50
and the prechamber housing 42 include surfaces that are generally
surfaces of revolution about the central longitudinal axis LA. The
precombustion chamber 34 has a predetermined geometric shape and
volume. In embodiments, the volume of the precombustion chamber 34
is smaller than the volume of the main combustion chamber 30. In
some embodiments, the volume of the precombustion chamber 34 is in
a range between about two and about five percent of the total
uncompressed volume of the main combustion chamber 30.
In the illustrated embodiment, the prechamber housing 42 includes
an upper member 54 and a lower member 57, which are threadingly
secured together. In other embodiments, other types of engagement
between the upper member 54 and the lower member 57 can be used,
such as, welding, press fitting, and the like. The prechamber
housing 42 is hollow and is adapted to receive the ignition device
44 therein.
The ignition device 44 is mounted to the prechamber housing 42. The
illustrated lower member 57 of the prechamber housing 42 defines an
ignition device bore 59 which has an internal threaded surface 62.
The ignition device 44 has an external threaded surface 64 which is
threadedly engaged with the internal threaded surface 62 of the
ignition device bore 59. The ignition device bore 59 is in
communication with the precombustion chamber 34.
In the illustrated embodiment, the ignition device 44 comprises a
spark plug 67 with an electrode 69. The spark plug 67 is removably
mounted to the prechamber housing 42 such that the electrode 69 is
in communication with the precombustion chamber 34 and such that
the electrode 69 is substantially aligned with the central
longitudinal axis LA. The spark plug 67 is threadedly received in
the ignition device bore 59 with the electrode 69 exposed to the
precombustion chamber 34 by way of the ignition device bore 59. The
spark plug 67 can be adapted to be electrically energized in a
conventional manner.
In embodiments, at least one of the prechamber housing 42 and the
nozzle 50 define a supplemental fuel passage 72. The supplemental
fuel passage 72 is in communication with the precombustion chamber
34 and with the supplemental fuel source 27. In embodiments, the
fuel of the supplemental fuel source 27 can have a richer fuel/air
ratio than the fuel/air ratio of the fuel supplied directly to the
main combustion chamber 30 with which the prechamber assembly 25 is
associated.
In the illustrated embodiment of FIG. 1, the upper member 54 and
the lower member 57 of the prechamber housing 42 both define the
supplemental fuel passage 72. The illustrated upper segment defines
a fuel passage entry segment 74. The illustrated lower member 57 of
the prechamber housing 42 defines a plurality of precombustion
chamber fuel passage segments 76 which are circumferentially
arranged about the lower member 57 and in fluid communication with
the fuel passage entry segment 74 via a control valve cavity 78
defined between the upper member 54 and the lower member 57.
The control valve 48 is disposed within the prechamber housing 42
and is adapted to selectively occlude the supplemental fuel passage
72 to prevent a flow of fuel from the supplemental fuel source 27
to the precombustion chamber 34. The illustrated control valve 48
is disposed within the control valve cavity 78 and is interposed
between the fuel passage entry segment 74 and the precombustion
chamber fuel passage segments 76. The control valve 48 can be
adapted to selectively permit the flow of fuel from the
supplemental fuel source 27 into the precombustion chamber 34 of
the prechamber assembly 25 to further promote ignition within the
precombustion chamber 34. The control valve 48 can be adapted to
open and close with the engine's combustion cycle to prevent
contamination of the fuel with exhaust and/or prevent leakage of
fuel into the exhaust gases. The control valve 48 can be adapted to
prevent the gas product of combustion to flow from the
precombustion chamber 34 to the fuel passage entry segment 74 of
the supplemental fuel passage 72 during the compression,
combustion, and exhaust phases of the engine.
In embodiments, the control valve 48 can be any suitable control
valve, such as a check valve assembly including a free-floating
ball check having an open mode position--permitting the flow of the
fuel from the supplemental fuel source 27 to the precombustion
chamber 34--and a closed mode position--preventing gas flow from
the supplemental fuel source 27 to the precombustion chamber 34. In
other embodiments, the control valve 48 can be a shuttle type check
valve. In the illustrated embodiment, the control valve 48 is
similar in construction and function to the check valve shown and
described in U.S. Pat. No. 6,575,192.
The nozzle 50 includes a nozzle body 82 having a mounting end 84
and a distal tip 85. The nozzle body 82 defines the central
longitudinal axis LA which extends between the mounting end 84 and
the distal tip 85. The nozzle body 82 is hollow and includes an
outer surface 88 and an inner surface 89. The outer surface 88 and
the inner surface 89 are both surfaces of revolution about the
central longitudinal axis LA.
The mounting end 84 of the nozzle 50 is in abutting relationship
with the lower member 57 of the prechamber housing 42. Any suitable
technique can be used to provide a seal between the nozzle 50 and
the lower member 57 of the prechamber housing 42, such as, o-rings,
press fit, metal seals, gaskets, welding, and the like.
The mounting end 84 of the nozzle body 82 includes an annular
flange 92 that defines a seat 93 which can be engaged with the
cylinder block 22 and/or the cylinder head 24. The mounting end 84
of the nozzle body 82 defines an external circumferential groove 94
configured to receive a suitable sealing device 52 (e.g., an
o-ring) therein for sealing.
The nozzle body 82 projects from the cylinder head 24 such that the
distal tip 85 of the nozzle body 82 is disposed in the main
combustion chamber 30. Any suitable sealing technique can be used
to seal the interface between the nozzle 50 and the cylinder head
24 and/or the cylinder block 22, such as, a gasket, a taper fit,
and/or a press fit to isolate fuel, combustion gases, and engine
coolant therein.
The inner surface 89 of the nozzle body 82 defines an interior
chamber 95 which is open to and in communication with a distal
cavity 97 defined in the lower member 57 of the prechamber housing
42. The interior chamber 95 of the nozzle body 82 and the distal
cavity 97 of the lower member 57 together define the precombustion
chamber 34 of the prechamber assembly 25. The interior chamber 95
of the nozzle body 82 is open to the electrode 69 of the spark plug
67 and is in fluid communication with the supplemental fuel passage
72 via the precombustion chamber fuel passage segments 76 of the
lower member 57.
The mounting end 84 of the nozzle body 82 is generally cylindrical.
The nozzle body 82 includes a converging portion 98 disposed
adjacent the mounting end 84 and a distal cylindrical portion 99
adjacent the distal tip 85. The distal cylindrical portion 99 has a
smaller diameter than that of the mounting end 84.
The nozzle body 82 defines a plurality of orifices 101, 102, 103,
104 in the distal tip 85. The orifices 101, 102, 103, 104 are in
communication with the interior chamber 95 of the nozzle body 82
and with the main combustion chamber 30 when the prechamber
assembly 25 is installed in the cylinder head 24. The illustrated
orifices 101, 102, 103, 104 are substantially identical to each
other. Accordingly, it will be understood that the description of
one orifice is applicable to the other orifices, as well.
The orifices 101, 102, 103, 104 are circumferentially arranged
about the central longitudinal axis LA at substantially
evenly-spaced angular positions. The orifices 101, 102, 103, 104
are respectively symmetrically disposed about the central
longitudinal axis LA such that the orifices 101, 102, 103, 104
extend along substantially the same angle of inclination relative
to the central longitudinal axis LA. In embodiments, the orifices
101, 102, 103, 104 can extend along a different angle of
inclination relative to the central longitudinal axis LA. In still
other embodiments, at least one of the orifices 101, 102, 103, 104
can extend along an angle of inclination relative to the central
longitudinal axis LA that is different from at least one other of
the orifices 101, 102, 103, 104.
Preferably, the orifices 101, 102, 103, 104 are configured such
that the flow characteristics of a fuel/air mixture within the
precombustion chamber in a region adjacent the electrode 69 of the
spark plug is less turbulent and more laminar than that in the
cylindrical portion 99 adjacent the distal tip 85 of the nozzle 50
where the orifices 101, 102, 103, 104 are located. The orifices
101, 102, 103, 104 can be configured such that flows of burning
fuel respectively conveyed from the interior chamber 95 out through
the orifices 101, 102, 103, 104 are controllably directed away from
the nozzle body 82 in diverging relationship to each other,
controllably expanding the burning gases away from the distal tip
85 of the nozzle 50 into the main combustion chamber 30 in order to
facilitate the ignition and burning of the combustible mixture in
the main combustion chamber 30 over a larger volume at the same
time.
In embodiments, the nozzle body 82 can define any suitable number
of orifices to achieve the desired swirl/mixing characteristics
within the interior chamber 95 of the nozzle body 82 and the
desired flame discharge pattern in the main combustion chamber 30
resulting from the combustion phase in the nozzle 50. For example,
in the illustrated embodiment, the nozzle body includes six
orifices circumferentially arranged about the central longitudinal
axis LA at substantially evenly-spaced angular positions (about
sixty degrees apart from each other). In other embodiments, the
nozzle body 82 can define a different number of orifices, such as
eight or twelve orifices circumferentially arranged about the
central longitudinal axis LA at substantially evenly-spaced angular
positions (about forty-five degrees and about thirty apart from
each other, respectively). In still other embodiments, the nozzle
body 82 can define yet a different number of cooperating orifices.
In yet other embodiments, the nozzle body can define orifices that
have variable spacing between at least two pairs of adjacent
orifices.
Referring to FIG. 2, the first orifice 101 of the nozzle 50 is
shown in axial cross section. It should be understood that the
description of the first orifice 101 is applicable to the other
orifices 102, 103, 104, as well.
The nozzle body 82 includes an orifice surface 110 that defines the
orifice 101. The outer surface 88 defines an outer opening 112, and
the inner surface 89 defines an inner opening 114. The orifice
surface 110 defines an orifice passage 118 extending between, and
in communication with, the outer opening 112 and the inner opening
114. The orifice passage 118 is in communication with the interior
chamber 95 via the inner opening 114.
The orifice surface 110 includes a boundary surface 120, a first
protrusion 125, and a second protrusion 127. The first protrusion
125 and the second protrusion 127 both project from the boundary
surface 120 radially inwardly into the orifice passage 118. The
first protrusion 125 and the second protrusion 127 are generally
axially aligned and are both disposed adjacent the inner opening
114.
The illustrated boundary surface 120 is generally cylindrical and
has an upper portion 130 and a lower portion 132. The illustrated
boundary surface 120 comprises a symmetric surface of revolution
about a first orifice axis OA.sub.1. The first orifice axis
OA.sub.1 is disposed at the first angle of inclination .THETA.
relative to the central longitudinal axis LA.
The first protrusion 125 is configured to divert a flow 135 of a
fuel mixture/flame front entering the orifice passage 118 from the
inner opening 114 radially away from the boundary surface 120. The
first protrusion 125 includes a first protrusion passage surface
137 that is configured to divert the flow of the fuel mixture/flame
front entering the orifice passage 118 radially away from the
boundary surface 120. The illustrated first protrusion passage
surface 137 includes a first inclined surface 139 and a second
inclined surface 140. The first inclined surface 139 and the second
inclined surface 140 are in converging relationship to each other
and define a ridge 141 therebetween (see FIG. 3 also).
The first inclined surface 139 extends between the inner opening
114 and the ridge 141. The first inclined surface 139 is inclined
away from the boundary surface 120, moving from the inner opening
114 to the ridge 141. The second inclined surface 140 extends
between the ridge 141 and the boundary surface 120 at an
intermediate edge 143 thereof. The second inclined surface 140 is
inclined toward the boundary surface 120, moving from the ridge 141
to the intermediate edge 143.
As shown in FIG. 2, the flow 135 of the fuel mixture/flame front
entering the orifice passage 118 from the inner opening 114 tends
to be diverted radially away from the boundary surface 120 by the
first inclined surface 139 and the ridge 141. The second inclined
surface 140 provides a gradual transition between the first
protrusion 125 and the boundary surface 120 that helps enhance the
flow streamlines of the flow 135 of the fuel mixture/flame front
passing through the orifice passage 118.
The second protrusion 127 includes a second protrusion passage
surface 148 having a portion that substantially conforms to the
expected flow path of the flow 135 of the fuel mixture/flame front
at the location of the second protrusion 127. The illustrated
second protrusion passage surface 148 includes a convex surface 152
and a concave surface 154.
The convex surface 152 is disposed adjacent the inner opening 114.
The illustrated convex surface 152 is curved. The concave surface
154 is contiguous with the convex surface and is disposed axially
outward of the convex surface 152, moving from the inner opening
114 toward the outer opening 112. The illustrated concave surface
154 is curved. As shown in FIG. 2, the flow 135 of the fuel
mixture/flame front entering the orifice passage 118 from the inner
opening 114 tends to follow the shape of the concave surface 154 of
the second protrusion 127.
In embodiments, the first protrusion 125 and the second protrusion
127 can be configured based upon computer modeling. For example,
the first protrusion 125 can be configured based upon computer
modeling to divert the flow 135 of the fuel mixture/flame front
entering the orifice passage 118 radially away from the portion of
the boundary surface 120 from which the first protrusion 125
projects. In embodiments, the second protrusion 127 can be
configured based upon computer modeling to enhance flow streamlines
of the flow 135 of the fuel mixture/flame front passing through the
orifice passage 118. In embodiments, any suitable modeling
technique, such as, computational fluid dynamics, for example, can
be used to model an expected flow path of the flow 135 of the fuel
mixture/flame front through the orifice 101 in question.
In embodiments, a baseline orifice passage 158 can be defined by a
geometric projection of the boundary surface 120 between the outer
opening 112 and the inner opening 114. The baseline orifice passage
158 can be used to iteratively reach a protrusion configuration to
achieve a desired fluid flow result.
Referring to FIG. 3, the first protrusion 125 projects from the
upper portion 130 of the boundary surface 120. The first protrusion
125 can extend circumferentially over a segment 162 of the upper
portion 130. The illustrated first protrusion 125 comprises a first
arc segment that extends circumferentially around the boundary
surface 120 by approximately one hundred twenty degrees. In other
embodiments, the first protrusion 125 can have a different
configuration.
The second protrusion 127 projects from the lower portion 132 of
the boundary surface 120. The second protrusion 127 can extend
circumferentially over a segment 164 of the lower portion 132. The
illustrated second protrusion 127 comprises a second arc segment
that extends circumferentially over the boundary surface 120 by
approximately one hundred twenty degrees. In other embodiments, the
second protrusion 127 can have a different configuration.
The second protrusion 127 is discontinuous from the first
protrusion 125. The second protrusion 127 and the first protrusion
125 are in opposing relationship to each other, being substantially
evenly spaced circumferentially about the boundary surface 120. In
other embodiments, the relative positioning of the first protrusion
125 and the second protrusion 127 can be varied.
The respective first protrusion 125 and second protrusion 127 of
the orifices 101, 102, 103, 104 can help reduce the stresses
imposed upon the nozzle body 82 by the flame front discharged from
the interior chamber 95 through the orifices 101, 102, 103, 104. In
embodiments, each of the orifices 101, 102, 103, 104 can have at
least one protrusion with a different shape which is configured to
help diminish the erosive nature of the flows travelling
therethrough. In embodiments, the configuration of the orifices
101, 102, 103, 104 of the nozzle 50 can help increase the useful
life of the prechamber assembly 25 including the nozzle 50 by
helping to diminish the deleterious effects caused by the passage
of the fuel/air mixture through the orifices 101, 102, 103,
104.
Referring to FIGS. 4-6, another embodiment of a nozzle 250
constructed in accordance with principles of the present disclosure
is shown. The nozzle 250 is suitable for use in a fuel system
having a prechamber assembly constructed in accordance with
principles of the present disclosure. Referring to FIG. 4, the
nozzle 250 includes a nozzle body 282 that defines a plurality of
orifices 301, 302, 303, 304 in a distal tip 285 of the nozzle body
282. The orifices 301, 302, 303, 304 are in communication with an
interior chamber 295 defined by the nozzle body 282 and with the
main combustion chamber 30 when the prechamber assembly 25 is
installed in the cylinder head 24. The orifices 301, 302, 303, 304
of the nozzle body 282 are substantially the same. Accordingly, it
will be understood that the description of one orifice 301 is
applicable to the other orifices 302, 303, 304, as well.
Referring to FIG. 5, the nozzle body 282 includes an orifice
surface 310 that defines the orifice 301. The orifice surface 310
defines an orifice passage 318 extending between, and in
communication with, an outer opening 312 defined by an outer
surface 288 of the nozzle body 282 and an inner opening 314 defined
by an inner surface 289 of the nozzle body 282. The orifice passage
318 is in communication with the interior chamber 295 via the inner
opening 314. The orifice passage 318 extends along a second orifice
axis OA.sub.2 between the inner opening 314 and the outer opening
312.
The orifice surface 310 includes a boundary surface 320 and a
plurality of protrusions 325, 326, 327, 328. The illustrated
boundary surface 320 is generally cylindrical and comprises a
symmetric surface of revolution about the second orifice axis
OA.sub.2. Each of the plurality of protrusions 325, 326, 327, 328
projects from a lower portion 332 of the boundary surface 320
radially inwardly into the orifice passage 318. The plurality of
protrusions 325, 326, 327, 328 is in spaced relationship to each
other along the orifice axis OA.sub.2.
The illustrated plurality of protrusions 325, 326, 327, 328 is in
substantially evenly-spaced relationship to each other along the
orifice axis OA.sub.2. In other embodiments, the spacing between at
least two adjacent protrusions can be different from the spacing
between at least one other pair of adjacent protrusions in the
orifice along the orifice axis. The illustrated plurality of
protrusions 325, 326, 327, 328 extends along the second orifice
axis OA.sub.2 substantially between the inner opening 314 and the
outer opening 312. The illustrated nozzle 250 includes four
protrusions 325, 326, 327, 328 in each of the orifices 301, 302,
303, 304. In other embodiments, a different number of protrusions
can be provided.
Referring to FIGS. 5 and 6, each of the plurality of protrusions
325, 326, 327, 328 comprises a convex spherical portion. Each of
the protrusions 325, 326, 327, 328 is configured to divert a flow
335 of a fuel mixture/flame front entering the orifice passage 318
radially away from the boundary surface 320. The protrusions 325,
326, 327, 328 are configured to help diminish the erosive nature of
the flows travelling through the orifice 301.
In embodiments, at least one of the protrusions 325, 326, 327, 328
can be elongated along the orifice axis OA.sub.2 to form a
half-capsule shape. In yet other embodiments, at least one of the
protrusions 325, 326, 327, 328 can have an ellipsoid shape. In some
of such embodiments, at least one of the protrusions 325, 326, 327,
328 having an ellipsoid shape with its major axis extending in a
direction substantially along the orifice axis OA.sub.2.
Referring to FIG. 6, the plurality of protrusions 325, 326, 327,
328 is generally circumferentially aligned with respect to each
other about the boundary surface 320. In other embodiments, at
least one of the protrusions 325, 326, 327, 328 can be
circumferentially offset with respect to at least one other of the
protrusions 325, 326, 327, 328. The nozzle 250 of FIGS. 4-6 is
similar in other respects to the nozzle 50 of FIGS. 1-3.
Referring to FIG. 7, in other embodiments, a nozzle 350 constructed
in accordance with principles of the present disclosure can include
at least one orifice 401 having a protrusion 425 that comprises a
torus segment. The illustrated nozzle 350 is suitable for use in a
fuel system having a prechamber assembly constructed in accordance
with principles of the present disclosure.
The nozzle 350 includes a nozzle body 382 that defines the orifice
401. In embodiments, the nozzle body 382 can include a plurality of
orifices arranged circumferentially about the nozzle body 382, each
being substantially the same as the orifice 401 shown in FIG.
7.
The nozzle body 382 includes an orifice surface 410 that defines an
orifice passage 418 of the orifice 401. The orifice surface 410 can
include a boundary surface 420 and at least the protrusion 425
which projects from the boundary surface 420 radially inwardly into
the orifice passage 418. The illustrated boundary surface 420 is
generally cylindrical and comprises a symmetric surface of
revolution about a third orifice axis OA.sub.3.
The illustrated protrusion 425 is disposed in a lower portion 432
of the boundary surface 420 adjacent an inner opening 414 and
comprises a torus segment that extends circumferentially around the
boundary surface 420 by approximately one hundred twenty degrees.
The protrusion 425 is configured to divert a flow of a fuel
mixture/flame front entering the orifice passage 418 radially away
from the boundary surface 420. The protrusion 425 is configured to
help diminish the erosive nature of the flows travelling through
the orifice 401.
In other embodiments, the protrusion 425 can be located in a
different circumferential and/or axial position, have a different
size, and/or extend circumferentially around the boundary surface
420 by a different amount. In embodiments, the orifice surface 410
can include a plurality of protrusions, each being substantially
the same as the protrusion 425 shown in FIG. 7 and disposed in
spaced relationship to each other along the orifice axis OA.sub.3
defined by the orifice surface 410. The nozzle 350 of FIG. 7 can be
similar in other respects to the nozzle 250 of FIGS. 4-6.
Referring to FIGS. 8 and 9, in other embodiments, a nozzle 450
constructed in accordance with principles of the present disclosure
can include at least one orifice 501 having a plurality of
protrusions 524, 525, 526, 527, 528, 529 wherein at least one of
the protrusions 524, 525, 526, 527, 528, 529 is circumferentially
offset with respect to at least one other of the plurality of the
protrusions 524, 525, 526, 527, 528, 529 about a boundary surface
520 of the orifice 501. The illustrated nozzle 450 is suitable for
use in a fuel system having a prechamber assembly constructed in
accordance with principles of the present disclosure.
The nozzle 450 includes a nozzle body 482 that defines the orifice
501. In embodiments, the nozzle body 482 can include a plurality of
orifices arranged circumferentially about the nozzle body 482, each
being substantially the same as the orifice 501 shown in FIGS. 8
and 9.
The nozzle body 482 includes an orifice surface 510 that defines an
orifice passage 518 of the orifice 501. The orifice surface 510
includes the boundary surface 520 and the protrusions 524, 525,
526, 527, 528, 529 which each projects from the boundary surface
520 radially inwardly into the orifice passage 518. The illustrated
boundary surface 520 is generally cylindrical and comprises a
symmetric surface of revolution about a fourth orifice axis
OA.sub.4.
The illustrated protrusions 524, 525, 526, 527, 528, 529 project
from a lower portion 532 of the boundary surface 520. Referring to
FIGS. 8 and 9, each of the plurality of protrusions 524, 525, 526,
527, 528, 529 comprises a convex spherical portion. Each of the
protrusions 524, 525, 526, 527, 528, 529 is configured to divert a
flow of a fuel mixture/flame front entering the orifice passage 518
radially away from the boundary surface 520. The protrusions 524,
525, 526, 527, 528, 529 are configured to help diminish the erosive
nature of the flows travelling through the orifice 501.
Referring to FIG. 9, in the illustrated embodiment, the protrusions
524, 525, 526, 527, 528, 529 are arrayed in three rows 571, 572,
573 of protrusions 524, 525; 526, 527; 528, 529, respectively,
which are in alternating, offset axial relationship with each other
along the fourth orifice axis OA.sub.4. The respective protrusions
524, 525; 526, 527; 528, 529 of each row 571, 572, 573 are
circumferentially aligned with each other about the boundary
surface 520, as shown in FIGS. 8 and 9. Referring to FIG. 9, the
protrusions 526, 527; 528, 529 of the outer rows 572, 573 are
respectively axially aligned with each other along the fourth
orifice axis OA.sub.4. The intermediate row 571 is disposed between
the outer rows 572, 573. The protrusions 524, 525 of the
intermediate row 571 are respectively offset axially with respect
to the protrusions 526, 527; 528, 529 of the outer rows 572, 573
along the fourth orifice axis OA.sub.4. In other embodiments, the
protrusions 524, 525, 526, 527, 528, 529 can be disposed in a
different array pattern. In other embodiments, the protrusions 524,
525, 526, 527, 528, 529 can be located in a different
circumferential and/or axial position, have a different size,
and/or have a different shape. The nozzle 450 of FIG. 8 is similar
in other respects to the nozzle 250 of FIGS. 4-6.
It will be apparent to one skilled in the art that various aspects
of the disclosed principles relating to prechamber assemblies may
be used with a variety of engines. Accordingly, one skilled in the
art will understand that, in other embodiments, an engine following
principles of the present disclosure can include different
components and can take on different forms.
Referring to FIG. 10, steps of an embodiment of a method 700 of
making a nozzle for a member of a fuel combustion system of an
engine following principles of the present disclosure are shown. In
embodiments, a method of making a nozzle for a member of a fuel
combustion system of an engine following principles of the present
disclosure can be used to make any embodiment of a nozzle according
to principles of the present disclosure.
The illustrated method 700 of making a nozzle includes
manufacturing a nozzle body (step 710). The nozzle body is hollow
and includes an outer surface and an inner surface. The outer
surface defines an outer opening. The inner surface defines an
interior chamber and an inner opening. In embodiments, the nozzle
body is manufactured from a suitable material, such as a metal
alloy. In some embodiments, the nozzle body is made from a nickel
alloy.
An orifice surface is defined (step 720). The orifice surface
defines an orifice passage extending between, and in communication
with, the outer opening and the inner opening. The orifice passage
is in communication with the interior chamber via the inner
opening.
The orifice surface is defined such that the orifice surface
includes a boundary surface and a protrusion (step 730). The
protrusion projects from the boundary surface radially inwardly
into the orifice passage.
In embodiments, the nozzle body is manufactured and each orifice
surface is defined via additive manufacturing (also sometimes
referred to as "additive layer manufacturing" or "3D printing"). In
embodiments, any suitable additive manufacturing equipment can be
used. For example, in embodiments, a production 3D printer
commercially available under the under the brand name ProX.TM. 200
from 3D Systems, Inc. of Rock Hill, S.C., can be used.
In embodiments, the nozzle body is manufactured using additive
manufacturing such that the nozzle body includes a body wall
portion. The body wall portion includes the boundary surface. The
body wall portion circumscribes the orifice passage and extends
between the inner surface and the outer surface. The body wall
portion can be made from a first material having a first thermal
resistance value. The orifice surface can be defined using additive
manufacturing such that the protrusion is made from a second
material having a second thermal resistance value. In embodiments,
the second thermal resistance value is greater than the first
thermal resistance value.
In embodiments, the orifice surface is defined such that the
protrusion is configured to divert a flow of a fuel mixture/flame
front entering the orifice passage radially away from the boundary
surface. In embodiments, the flow of the fuel mixture/flame front
comprises at least one of an ignited fuel mixture for a prechamber
assembly and a fuel-injector fuel mixture for a fuel injector.
In embodiments, the shape of the protrusion is based upon the flow
of the fuel mixture/flame front through a geometric representation
of at least one baseline orifice passage is iteratively modeled to
define a shape of the protrusion. In embodiments, modeling is
performed that analyzes the flow of the fuel mixture/flame front
through a geometric representation of at least one baseline orifice
passage and at least two different protrusions having different
configurations. The baseline orifice passage can be defined by a
projection of the boundary surface between the outer opening and
the inner opening without any protrusions therein. The protrusion
of the orifice surface has a shape based upon the modeling. Any
suitable modeling technique, such as, computational fluid dynamics,
for example, can be used to model an expected flow path of a flow
of fuel mixture/flame front through the baseline orifice passage.
In embodiments, the shape of at least one projection can be
configured to include a protrusion passage surface that
substantially conforms to the expected flow path of the flow of the
fuel mixture/flame front at the location of that projection through
at least one baseline orifice passage. In other embodiments, the
shape of at least one projection can be configured to include a
protrusion passage surface that is configured to divert the flow of
the fuel mixture/flame front entering the orifice passage radially
away from the boundary surface.
INDUSTRIAL APPLICABILITY
The industrial applicability of the embodiments of fuel combustion
systems, nozzles for a member of a fuel combustion system of an
engine, and methods of making nozzles for a member of a fuel
combustion system of an engine as described herein will be readily
appreciated from the foregoing discussion. In embodiments, a nozzle
constructed according to principles of the present disclosure can
be used in a suitable member of a fuel combustion system of an
engine, such as, a fuel injector or a prechamber assembly, for
example. Embodiments of a nozzle and/or a fuel combustion system
according to principles of the present disclosure may find
potential application in any suitable engine. Exemplary engines
include those used in electrical generators and pumps, for
example.
For example, in internal combustion engines, above a particular
capacity, the energy of an ignition spark may no longer be
sufficient to ignite reliably the combustion gas/air mixture, which
for emissions reasons is often very lean, in the main combustion
chamber. To increase the ignition energy, a prechamber assembly
constructed according to principles of the present disclosure can
be connected to the cylinder head and placed in communication with
the main combustion chamber via a plurality of orifices defined in
the nozzle. A small part of the mixture is enriched with a small
quantity of combustion gas or an additional fuel and ignited in the
precombustion chamber. Flame propagation, i.e. ignition kernel, is
transferred to the main combustion chamber by way of the orifices
in the nozzle and the flame propagation ignites the lean fuel
mixture. The flame pattern emitting from the nozzle is advantageous
because it has a hot surface area that can ignite even extremely
lean or diluted combustible mixtures in a repeatable manner.
Embodiments of a nozzle constructed according to principles of the
present disclosure can have an orifice configuration that helps to
reduce the heat transfer between a flow of fuel mixture/flame front
passing through the respective orifice of the nozzle and the nozzle
body and to reduce the temperature within the orifice passages and
the orifice bridges disposed around the nozzle body. In
embodiments, the nozzle can include an orifice surface having at
least one protrusion configured to modify a flow of a fuel
mixture/flame front passing through the orifice passage defined by
the orifice surface to help reduce at least one of the temperature
within the orifice passage and the heat transfer between the flow
of a fuel mixture/flame front and the boundary surface of the
orifice surface.
In embodiments, a nozzle constructed according to principles of the
present disclosure can include an orifice surface having a boundary
surface and a protrusion where the protrusion projects from the
boundary surface radially inwardly into the orifice passage. By
introducing a rippled surface in the orifice, fluid detachment can
occur, thereby reducing the overall heat transfer between the flow
of fuel and the boundary surface and reducing the temperature at
the boundary surface.
The improved heat transfer characteristics can help reduce the
amount of heat-induced damage suffered by the nozzle body during
operation. The orifices of the nozzle can be configured to help
increase the useful life of the nozzle.
Embodiments of a nozzle constructed according to principles of the
present disclosure can be made using additive manufacturing
techniques. The protrusions in the orifices can be made using
additive manufacturing techniques from a material having a higher
thermal resistance value than the material used to make the
surrounding body wall portion. The higher thermal resistance of the
protrusions can increase their useful life and help them withstand
the ablative nature of the flows of fuel mixture/flame front
passing through the orifices.
It will be appreciated that the foregoing description provides
examples of the disclosed system and technique. However, it is
contemplated that other implementations of the disclosure may
differ in detail from the foregoing examples. All references to the
disclosure or examples thereof are intended to reference the
particular example being discussed at that point and are not
intended to imply any limitation as to the scope of the disclosure
more generally. All language of distinction and disparagement with
respect to certain features is intended to indicate a lack of
preference for the features of interest, but not to exclude such
from the scope of the disclosure entirely unless otherwise
specifically indicated.
Recitation of ranges of values herein are merely intended to serve
as a shorthand method of referring individually to each separate
value falling within the range, unless otherwise indicated herein,
and each separate value is incorporated into the specification as
if it were individually recited herein. All methods described
herein can be performed in any suitable order unless otherwise
indicated herein or otherwise clearly contradicted by context.
* * * * *